1. Technical Field of the Invention
This invention concerns in general those means, installed on tyre removal machines, which enable the tyre to be removed from and/or mounted on the wheel rim. The wheel rim comprises two lateral bead retaining flanges onto which the beads of the tire rest.
2. Prior Art
To mount tyres on their wheel rims, and to effect the opposite operation, machines are known comprising essentially a rotary platform of vertical axis provided with a self-centering device for locking the wheel rim, which is overlaid by a support which supports, adjustable in height and in the horizontal direction, a tool arranged to interact with the tyre edge or bead, to urge it below, or extract it from, the flange of the wheel rim.
In known machines said tool is positioned at the end of a vertical support bar which slides within the end seat of a horizontal arm, to which it can be locked in level.
The horizontal arm itself slides in the end seat of a vertical plate which extends upwards from the machine base to the side of the platform which receives the tyre.
Said horizontal arm is provided with means for locking it in the desired position.
The known art teaches that to be able to remove a tyre from the wheel rim the first operation which the operator has to carry out is to detach the tyre bead from the bead retaining flange of the wheel rim using the bead release device with which tyre removal machines are usually provided. The operator, after the tyre bead has been detached from the bed retaining flange, places the wheel, comprising the wheel rim and tyre, on the self-centering device and locks it in the working position.
At this point the operator positions the tool in contact with the flange of the wheel rim and, using a suitable lever, lifts the tyre bead above the working surface of the tool and then rotates the wheel rim while simultaneously pressing with one hand on that side of the tyre opposite that at which the tool is positioned, in order to enable the bead to position itself in the well of the wheel rim. In addition, while the wheel rim is rotating, the operator has to aid the escape of the bead using a lever, one end of which is inserted between the tyre edge and the flange of the wheel rim.
In contrast, to mount the tyre on the wheel rim, the operator firstly locks the wheel rim on the self-centering device, then positions the tyre on the wheel rim and then by pressing on its upper side has to at least partially insert the lower bead of the tyre into the wheel rim. At this point, the operator locates the tool in its working position, and in particular has to position a part of the tyre bead below the working surface of the tool. He then rotates the self-centering device and with his hands, by pressing on the side of the tyre, aids the insertion of the bead into the bead retaining flange of the wheel rim.
It should be noted that both during the mounting of the tyre onto the wheel rim and during its removal, the operator usually lubricates the edge of the tyre bead to facilitate its mounting onto or its removal from the wheel rim.
Although devices of known type perform their proposed functions they always require the intervention of the operator, and require from him a physical force the extent of which depends on the size of the tyre and the rigidity of its bead.
In addition, the manual intervention of the operator means that he is subjected to the risk of accidents, as he has to work with moving equipment and in contact with lubricated surfaces.
An object of the present invention is to overcome the drawbacks of the known art within the framework of a rational and reliable solution, which does not require the operator to intervene actively during the removal of the tyre from the wheel rim, or during the opposite operation.
A further object of the invention is to provide a device which accelerates the tyre mounting and removal operations.
The invention attains said objects by virtue of an automatic device for mounting and removing the tyre on/from the wheel rim which, associated with rotary means for supporting the wheel rim, is able to extract and/or insert the tyre from/into the wheel rim without requiring any operator intervention.
According to the invention the device comprises an operating head provided with a demounting tool. The demounting tool is hinged to the operating head, and is arranged to grip the tyre and then extract it from the wheel rim.
In greater detail, said demounting tool can pivot about the hinging axis to position itself between at least one first position in which the tyre bead is gripped and at least one second position in which the tyre bead is extracted from the wheel rim.
The operating head can rotate about its axis, and is associated with means which enable it to translate horizontally and vertically in such a manner as to position the demounting and mounting tools in proximity to the flange of the wheel rim.
The wheel rim support means must preferably be such as to leave both flanges of the wheel rim free, so that the device of the invention can act simultaneously on both sides of the wheel rim.
The wheel rim support means can translate horizontally to approach and withdraw from the mounting-demounting tool of the invention in accordance with the wheel rim diameter and possibly the operating position assumed by the mounting and demounting tools.
Finally, the combination of the device of the invention with said rotary support means for the wheel rim results in an assembly representing a complete tyre removal machine which can also be easily provided with a bead release tool of known type.
The particular characteristics of the invention are defined in the claims.
The constructional and operational characteristics will be more apparent from the ensuing description of a preferred embodiment thereof given by way of non-limiting example and illustrated in the accompanying drawings.